Draw sheet for rotary printing presses



Nov. 16, 1937. R. R. LEWIS 2,099,024

DRAW SHEET FOR ROTARY PRINTING PRESSES Filed Nov. 8, 1955 @www INVENTOR BY i i- ATTORNEYS Patented Nov. 16, 1937 UNITED STATES 2,099,024 DRAW SHEET FOB ROTARY PRINTING PRES SES

Robert a. Lewis, Baldwin, N. Y., minor to vuican Proofing Company, New York, N. Y., a corporation of New 'York Application November 8, 1933, Serial No. 697,101

lClahn.

My invention relates to a new and improved draw sheet for packing the impression cylinders of rotary printing presses.

Another object of my invention is to provide an impression-receiving member which can be used on any suitable under-packing.

Another object of my invention is to provide a surface member of uniform and accurate thickness, and which shall be smooth, oil-repellent, strong, resilient, and having the necessary rmness.

Other objects cf my invention will be set forth in the following description and drawing, it being understood that the above general statement of the objects of my invention is intended to generally explain the same, without limiting it in an manner.

A number of different materials have been previously used for making the surface member of an impression packing. For example, the surface member has been made of manila paper and the under-packing has been made of softer paper.

Likewise the surface member or draw sheet has been made of fabric which has been coated with nitro-cellulose material, fabric coated with rubber, and uncoated fabrics of various kinds have been used.

According to my invention the improved draw sheet or surface member includes two layers Il and I2 of light and strong cotton fabric, which are cemented by means of an intermediate layer of adhesive I0. Said intermediate layer may be an ordinary rubber cement, of the kind which is used for connecting fabrics to each other.

Fabric layers II and I2 are preferably identical and I prefer to use grade A Airplane cloth, the specification of which is as follows:-

Two ply mercerized yarn, plain weave, thread count warp 80, filling 80, weight 4.5 ounces per square yard, minimum breaking strength 80 pounds each way by the strip method, thickness .010 inch.

'Ihe rubber cement I0 should be a firm and resilient stock which is not readily destroyed by contact with oils and solvents.

While I do not wish to be limited to the ingredients and proportions specified herein, a satisfactory example of said rubber cement is as fol- Pounds Oz.

Rubber 30 Zinc oxide 25 8 Antimony sulphide 5 4 Sulphur 3 Aldol-alpha-napthylamine 6 Lime 6 D. P. G 5.4 Stearic acid .5

'Ihe function of the zinc oxide is to activate the accelerator. It also acts as a ller.

The function of the antimony sulphide is to provide desirable color.

The function of the lime is to reduce porosity.

The D. P. G. is the commercial name for an accelerator, whose chemical name is diphenyl guanidine.

The function of the stearic acid is to eliminate the variables in the crude rubber.

The sulphur is utilized for vulcanizing the material, and the function of the aldol-alphanapthylamine is to serve as an anti-oxidant.

The compound specied in said example or formula is preferably dissolved in a suitable solvent such as gasoline, and the compound is then applied to the fabric layers II and I2 by means of the well known spreading process, by means of which the cement is spread in a succession of thin layers. Enough solvent is added to render the compound viscous, so that it can be spread in the usual way.

The rubber can be applied to the fabric layers II and I2 by means of a calender, but a more uniform thickness can be secured by spreading.

After the cement has been applied to a face of each of said fabric layers II and I2, the coated surfaces are pressed together by passing the layers II and I2 through rolls.

'The combined thickness of the two layers of fabric I I and I2, and the intermediate rubber layer III, should be about .005 inch less than the desired finished thickness. For most purposes the final thickness desired is from .025 to .030 inch. The thickness of each fabric layer may be about .010 inch and the thickness of the intermediate rubber cement layer can be about .005 inch when the material is passed through the rolls.

Instead of using rubber, I can use any cement having the desired resilience, exibility and firmness. For example, I can use certain synthetic resins such as phenol-formaldehyde condensation resins, and the resins made by reacting glycerine and phthalic anhydride. Likewise I can use the synthetic and rubber-like product which is described in United States Patent No. 1,829,502, this being a polymer of divinyl acetylene.

A surface coating I3 is now'applied to one of the fabric layers. This surface coating should be flexible, resilient, tough, and oil-repellent. I prefer to use a surface coating which is Acomposed essentially of a reaction product, obtained from the interaction of ethylene dichloride and sodium polysulphide. I can use other related coating materials, made by reacting halogen substituted olenes and alkaline polysulphides.

Likewise I can use other coating materials having a base of nitro-cellulose, cellulose acetate,

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phenol-formaldehyde condensation resins, resins made by reacting glycerine and phthalic anhydride. I can also use oxidized linseed oil and the like. v

The general method of manufacture of the surface element is set forth in United States Patent No. 1,846,810 issued on February 23. 1932 to Lewis, et al.

In addition to the details oi' manufacture specified in this patnt, I prefer to pass the element, after it has been cured and cooled. through a bumng and polishing machine. This machine consists essentially of two drums which revolve at high speed. One of these drums is covered with fine emery cloth or other abrasive cloth or material, and the other drum is covered with carpetlng or other suitable bumng material. The cured and cooled article is pulled under tension through this machine, a number of times, until all the surface blemishes of the surface coating have been removed, and a smooth and highly polished surface is secured.

'I'he use of the rubber layer between the fabric layers, produces greatly increased surface resilience so that the printing is much superior and the life ofl the draw sheet is greatly increased.

It has been previously well known to make the underblankets of the packing from material which includes rubber but it was thought that it was vsecured if the draw sheet itself is resilient.

In the completed article the thickness of the 4surface coating is .005 inch so that the complete finished draw sheet has a total thickness of .030 inch. if the thickness of the fabric layers Il and I2, and the thickness of the rubber layer i0, is as previously specified.

I have shown a preferred embodiment-of my invention. but it understood that numerous changes and omissions could be made without departing from its spirit.

I claim:

A draw sheet comprising fabric layers having an intermediate resilient layer which connects said fabric layers, one of said fabric layers having an oil-repellent coating which serves to protect said resilient layer as well as the blanket over which the draw sheet fits, the thickness of said draw sheet not substantially exceeding .030 inch.

ROBERT R. LEWIS. 

